Doxycycline and Tetracycline Interaction
Drug interaction information between Doxycycline and Tetracycline.
Doxycycline and Tetracycline have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Doxycycline and Tetracycline. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
Both of these medicines belong to the same family of antibiotics, which can increase the risk of side effects without helping you get better faster.
What To Do
Avoid taking these two antibiotics together unless your doctor tells you otherwise.
FDA Label Information
Drug Interactions Because tetracyclines have been shown to depress plasma prothrombin activity, patients who are on anticoagulant therapy may require downward adjustment of their anticoagulant dosage. Since bacteriostatic drugs may interfere with the bactericidal action of penicillin, it is advisable to avoid giving tetracyclines in conjunction with penicillin. Absorption of tetracyclines is impaired by antacids containing aluminum, calcium, or magnesium, and iron-containing preparations.
Doxycycline Also Interacts With
- Rifampin moderate
- Carbamazepine minor
- Bismuth Subsalicylate minor
- Phenytoin minor
- Doxycycline Hyclate minor
Tetracycline Also Interacts With
- Theophylline major
- Doxycycline Hyclate moderate
- Minocycline moderate
- Zinc Sulfate minor
- Atovaquone/Proguanil minor
Frequently Asked Questions
Can I take Doxycycline and Tetracycline together?
This is a moderate interaction. Avoid taking these two antibiotics together unless your doctor tells you otherwise.
How serious is the interaction between Doxycycline and Tetracycline?
This interaction is classified as "moderate" severity by the FDA. Moderate interactions may worsen your condition or change how your medications work.
Why do Doxycycline and Tetracycline interact?
Both of these medicines belong to the same family of antibiotics, which can increase the risk of side effects without helping you get better faster.
Understanding the Doxycycline and Tetracycline Interaction
FDA-approved prescribing information for these two drugs flags their combination as a moderate-severity interaction. Doxycycline belongs to the Tetracycline Antibiotic class and Tetracycline belongs to the Tetracycline Antibiotic class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Both of these medicines belong to the same family of antibiotics, which can increase the risk of side effects without helping you get better faster. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Doxycycline has 9 total documented interactions on file in this dataset, and Tetracycline has 12. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Avoid taking these two antibiotics together unless your doctor tells you otherwise. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Doxycycline or Tetracycline based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.